1. Field of the Invention
This invention is related to a calcium containing composition derived from the shell of sea urchin which gives high oral bioavailability, manufacturing method of such a composition, food containing such a composition, feed containing such a composition, and pharmaceutical compositions containing such a composition.
2. Description of the Related Art
Various types of calcium formulations and health food which contain calcium as an active component have been proposed to supplement dietary calcium thus far. The calcium used for such formulation and health food is generally made from calcium carbonate derived from mineral origin such as limestone and lime milk, calcium phosphate, calcium hydroxide, calcium lactate, calcium gluconate, shellfish derive calcium such as oyster shells, other mollusks shells and corals, crustaceans such as crabs, and shrimps, seaweeds such as tangles, hijikia, and undaria, mammalian bones, egg shells, and so forth.
However, the calcium made from these materials generally does not give sufficient oral bioavailability. Furthermore, oral bioavailability of calcium in human is generally extremely low unless it is administrated with Vitamin D or proteins and it is difficult to supply the required amount of calcium to human by itself. In addition, people in Japan take only 531 mg per day of calcium in average according to the National Nutrition Investigation Report by the Ministry of Health and Welfare. This level is less than a half of that in the Western countries.
Under such circumstances, the inventors herein have tried to find a calcium containing composition with high oral bioavailability. As a result, the invention herein was achieved by discovering that a calcium containing composition with high oral bioavailability can be obtained, to our astonishment, by baking sea urchin shells which have been disposed without any use.